To Whom It May Concern:

I am actually not a medical student :p
I am a programmer, writing some entertainment softwares :)

The other day I was talking to a guy and we wonder, if human can node his index finger fast, constantly, mean time use the other 4 fingers to grasp and open, grasp and open irregularly?
or node index finger constantly plus node thumb irregularly?

I remember I saw somewhere in a science book when I was a kid, that there's some limitations?

I've searched hard on the internet...
but didn't really find anything related... or some are hard for me to understand... orz

If someone can kindly tell me the answer or show me a link that would be grateful~

Regards,

Experiment around yourself--it seems like I can do both of the functions you described (assuming I understood correctly). I think a lot of it is how in touch you are with your body. It is fun to experiment with and definitely good motor skill practice

Okay, here's the thing, you can move some of your fingers independently and some not. The reason is because of anatomy. Some of your fingers are connected to the same muscle, in other words, the same muscles are used to move multiple fingers. Now this is why when you move one finger down, the rest can be moved slightly along with it. It's really got to do with anatomy not neuroscience, when you try to move one finger, the muscle contracts and the tendon pulls the finger. However since it's basically on the same muscle, more than one finger can be pulled at the same time. It's actually a bit more complicated but I don't want to confuse you with anatomical bable lol.

Basically, the answer to your question is when one finger moves it can cause the tendons of other fingers to be pulled as well - which is why when you move one finger others can follow.

Go look up arm/hand anatomy, specifically the pronatior and supinatior muscles of the arm. Gray's Anatomy is a good book.

pianists have to be able to move them independently

I bet you could move all fingers independently without motion of the other fingers, you would just need a little hand yoga

If I touch my middle finger to my palm with my other fingers extended, my ring finger comes down slightly; however, my ring finger does not HAVE to come down. If I press gently, I can bring my other fingers back to the starting position. It seems to me that it is definitely possible, it just takes a lot of mind body coordination (and practice).

yeah~ thx for all the replys~~~
and thanks for reading my poor english :)

I think Mr. maximus242's answer is close to what I was imaging?
I don't mean moving finger independently without other finger's pulling force.

maybe I explain wrong by saying 'node' your fingers, it should be more like 'pulling trigger' action :p
I've talked to another 3 friends, tell them to follow my action.
somewhat can, not so smooth, and not sure still can if without focusing.
I play violin pretty well, but I do feel a little weird when I do this...


then...
when I hold a gun,
fire MADLY,
can people easily dis-attach their thumb then attach (hold gun, tide) again repeatedly (different interval than pulling trigger, slower. attach then hold for a very short time, something like 0.6 ~ 1.x seconds, a short time) but totally not affecting each other?
It's easy to hold then fire (thumb first, then index-finger), but when dis-attach then attach the thumb...
during that, I would image people would stop their index finger? or maybe their thumb will move... weird? feel weird?

from Flex's example, can practice fix this? maybe just not familiar?


but then...
when I hold a game-pad,
I place my thumb on the analog stick (once and don't lift up irregularly) to control game character's view angel,
and then repeatedly hitting R button (right shoulder button at the back) with my index finger.
I can control the view angel (rotate my thumb) and fire together without disturbing,

Is this because rotate uses different muscles then hitting?

but if I need to PRESS DOWN the analog stick before rotate,
one PRESS DOWN can only rotate +-30 degrees,
you have to RELEASE then PRESS DOWN if you want to move from the current angle to another +-30 degrees.
maybe the index-finger would be interrupted?


--
talking about confuse XD
I fould some articles with all those experiment, devices photo, readings from the experiment, reference list, cited list...
OMG! orz
not sure if this is what I am looking for...

Abidextrious thumbs are a part of human evolution. Thumbs have their own muscles and two tendons. Pianists move their fingers down independently, but the rest of their fingers are pushed down slightly.

However, the force pulling down the other fingers is not significant enough to push down the piano key. Have a pianist hold their fingers in mid air and move one down - you will see the other fingers will move down as well.

The reason why you do not see multiple fingers move down at the same time while playing piano keys is because the force generated is not great enough. You do have individual finger muscles, but the majority of the pulling force of your hand is located in muscles in your arm, not your hand.

You may be able to partially prevent your fingers from moving together by pulling the fingers you do not want moved up - and the ones you do want to move - down. This would cause your muscles to be pulling your fingers up and down at the same time. Then it becomes a question of which side is given more force.

However, by doing that, your fingers will be very stiff and tight. Overall human anatomy makes it so that your fingers will always move at least a little bit in cohesion with each other.

If you really wanted to make your fingers completely independent it would probably require surgery.

I have been practicing recently, stretching the muscles in my forearm by applying gentle pressure to my fingers. I can now move one finger down independently with less motion from my other fingers, and by focusing, I can lift the other finger nearly back to the starting position. I am really begining to think it is just a matter of hand yoga. Were you to try and hug your legs, I am sure you would not be able to without practice, this is not to say it can't be done. You may be able to touch your toes, but in time, the act can be performed.

starting position? you mean the position when you stretch straight?
I think I can do that too~ XD
my finger is softer than normal people, I can fold backward all my fingers without force
like this \_ and I can also do /\_,

I can stretch all my finger above normal as well

　　\__
finger palm

but that is, if I move slowly, if I move fast, the nearby fingers will move up and down too...

--
piano and hold gun...
chosing which is greater force...

when playing piano (or violin, computer keyboard) I guess there's no much force generated on each finger than holding?
you open you hand and your muscles is kinda relaxed?
but when holding a gun, or Wii remote (Controller from a New Console, simmilar to holding a gun I guess) or maybe hair drier?
I do fell... hnnnn maybe because I roll up my fingers? muscles are tensed? (I can see the muscle around my wrist moved when I roll up my fingers.) when I madly hitting B (trigger at the back), feel weird to hit A...
sometimes my thumb will tremble... and hitting like the index finger?
It is a lot easier if I stop my index finger during thumb release -> press action.
or maybe I'm abnormal...? (maybe my friends too...) ="=

Try this quick test:

1. Spread your hand flat on a table, palm down. Then move each finger off the table, one at a time, with the other four in contact. Easy.

2. Turn your hand over, and spread it so the back of your hand and all your fingernails touch the table. Repeat lifting fingers one at a time. It's a little harder, especially for the middle finger, but it should be doable for most people.

This should settle the question of single finger motion.

My point was that you have to push the other fingers down onto the table in order to lift up one independently. If you try to lift one finger without pushing down your other fingers, they move.